1. Field of the Invention
The present invention relates to a film formation apparatus used for forming a film on a surface of a body to be processed, and particularly, relates to a film formation apparatus by use of a DC magnetron method using a sputtering method which is one of several thin film forming methods.
2. Background Art
Conventionally, a film formation apparatus using a sputtering method (hereinafter, refer to “sputtering apparatus”) is used in a film formation step in which, for example, a semiconductor device is manufactured.
As a sputtering apparatus of such intended use, with miniaturizing of wiring pattern in recent years, an apparatus is increasingly and strongly required in a film can be formed over an entire substrate W to be processed with excellent coatability in microscopic holes having a high-aspect ratio such as the ratio of the depth divided by the width exceeding three, that is, improvement of coverage is strongly required.
Generally, in the aforementioned sputtering apparatus, a magnet assembly which is constituted of a plurality of magnets having alternately different polarities is disposed behind, for example, a target (opposite side of a sputtering face of a target).
This magnet assembly generates a tunnel-shaped magnetic field at the anterior target (space to which a sputtering face is exposed), the electron density is improved at the anterior target and the plasma density becomes high as a result of capturing electrons which are ionized at the anterior target and secondary electrons generated by sputtering.
In such sputtering apparatus, the region of the target which is affected according to the above-described magnetic field is preferentially sputtered.
Consequently, in terms of improvement of stability of the electric discharge, efficiency in the use of target, or the like, if the above-described region located near, for example, the center of the target, the amount of erosion in the target increases near the center thereof when sputtering is carried out.
In such case, the target material particles sputtered from the target (e.g., metal particles, hereinafter referred to as “sputtered particles”) are adhered to a peripheral portion of the substrate at an angle which is inclined with respect to a vertical direction of the substrate.
As a result, in the case where the sputtering apparatus is used for the aforementioned film formation step, particularly, it is conventionally known that a problem of asymmetric coverage being formed at the peripheral portion of the substrate.
Particularly, in the cross-sectional face of the microscopic holes formed at the peripheral portion of the substrate, there is a problem in that the shape of a coat formed between the bottom of the microscopic holes and one of the side walls thereof is different from the shape of a coat formed between the bottom of the microscopic holes and the other of the side walls thereof.
In order to solve the foregoing problem, a sputtering apparatus is known in, for example, Japanese Unexamined Patent Application, First Publication No. 2008-47661, the apparatus includes a first sputtering target and a second sputtering target, the first sputtering target is disposed above a stage on which a substrate is mounted in a vacuum chamber and is substantially parallel to the top face of the stage, and the second sputtering target is disposed at obliquely upside of the stage so as to face in a diagonal direction with respect to the top face of the stage, that is, the apparatus provided with a plurality of cathode units.
However, as in disclosure of Japanese Unexamined Patent Application, First Publication No. 2008-47661, when cathode units are disposed inside the vacuum chamber, the constitution of the apparatus becomes complicated, sputtering power sources or magnet assemblies are also necessary in accordance with the number of targets, the number of components increases, there is a problem in that the cost thereof increases.
Furthermore, the efficiency in the use of the target deteriorates, and there is a problem in that the cost of manufacturing increases.